Information transmission systems often include scrambling and unscrambling means to provide privacy. The information is rendered unintelligible when sent over a transmission channel, and is then again, rendered intelligible after reception. Scrambling and unscrambling means are also very important for providing more reliable transmission over noisy or interrupted communications channels. The errors introduced by the imperfections in the transmission channel affect the scrambled transmitted information and commonly have time durations spanning a plurality of information bits. When the information is received and unscrambled, the erroneous bits are given a random distribution throughout the data sequence, which minimizes the effects of the erroneous bits and improves the effectiveness of error detection and correction apparatus.